Axle shaft cover plate with bearing assembly

ABSTRACT

A cover plate for a drive assembly that includes a bearing housing having a bearing cavity, a thrust bearing axially disposed within the bearing cavity that includes a cup, cone and plurality of rollers disposed between cup and cone raceways, a thrust plate with an axle engaging surface disposed perpendicular to a central axis and coupled for rotation to the cone. The cover plate may be connected to a final drive housing of a final drive that includes a plurality of gears operatively connected to an axle shaft, the end of the axle shaft positioned to rotationally engage the thrust plate and cone.

TECHNICAL FIELD

The present disclosure relates generally to axle and final driveassemblies for heavy machinery, and more particularly to an axleassembly including a cover plate having a bearing assembly forengagement of an end of an axle shaft.

BACKGROUND

A conventional power train for vehicles, particularly for heavyindustrial machinery such as that used in forestry, landfill operations,agriculture, mining, construction, material handling, tunneling,drilling and other industries, often includes a power source that isoperatively connected to the driven traction devices, such as the rearwheels of a wheeled machine, through an axle shaft connected to a finaldrive assembly. The final drive assembly typically consists of a gearset that is designed to alter the rotational speed and torquetransmitted from the axle shaft to the traction devices of the machine.Examples of machines employing such arrangements may include, forexample, loaders, motor graders, dozers, excavators, compactors, watertrucks, articulated trucks, dump trucks, tractors, material handlers,and similar heavy mobile equipment.

For example, in an off-highway truck or tractor, such as an off-highwaydump truck, an engine or other power source may be operatively connectedthrough a transmission to a rear differential that is configured totransmit rotational power to the rear wheels disposed on opposing sidesof the machine. The two axle shafts extending from the rear differentialmay be connected through a sun gear to the final drive includingplanetary gears, carriers, pins, and additional sun gears, as is wellknown in the art. Such final drives are configured to provide areduction in rotational velocity with an accompanying increase in torquedelivered to the driven rear wheels of the machine. The final drivetypically includes a final drive housing having an external cover platethat can be removed for access to the axle shaft and final drivecomponents. In some configurations, the cover plate may also serve torestrict axial movement of the associated axle shaft during operation.However, this can lead to distortion and wear of both the axle shaft andthe cover plate. To resolve this issue, it is known to include areplaceable wear plate that is affixed to the internal surface of thecover plate. The axle shaft is disposed against the wear plate duringoperation, the axle shaft rotating at a higher velocity than the coverplate and affixed wear plate due to the reductive final drive.

To decrease the time associated with maintenance and replacement of thecentrally disposed axle shaft, it is also known to provide a cover platethat includes an outer cover plate and an inner, smaller cover plate,wherein the smaller cover plate may be removed without having to fullydrain lubricant from the final drive housing to access and/or remove theaxle shaft. A wear plate has been attached to an inner surface of theinner cover plate to engage the axle shaft. In this regard, removing thesmaller cover plate also provides a more efficient method forreplacement of the wear plate.

While the wear plate can reduce the stresses to the axle shaft andreduce wear to both the axle shaft and an unprotected cover plate, theaxle shaft can still be subject to wear, distortional stresses and theassociated decreased performance and/or axle failure. The presentdisclosure is directed to an improved cover plate, thrust plate andbearing assembly that addresses one or more of the problems orshortcomings set forth above.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure provides a drive assembly for amobile machine that includes an axle shaft having an outer end and acentral axis, and a final drive having a plurality of gears operativelyconnected to the axle shaft contained within the final drive housing.Connected to the final drive housing is a cover plate assembly thatincludes a bearing housing, thrust bearing and thrust plate. The bearinghousing includes a first end, a second end, and an axially alignedbearing cavity, the bearing cavity defined by an interior housingsurface that extends between an opening at the second end of the bearinghousing and an interior end wall. The thrust bearing is axially disposedwithin the bearing cavity, and includes a cup with a cup raceway, a conewith a cone raceway positioned opposing the cup raceway, and a pluralityof rollers positioned between the cup and cone raceways. The thrustplate includes an axle engaging surface disposed perpendicular to thecentral axis, and is rotationally coupled to the cone. The outer end ofthe axle shaft is positioned to rotationally engage the axle engagingsurface so that the axle, thrust plate and cone rotate as a single unit.

In another aspect, provided is a cover plate for a drive assembly, thecover plate generally including a bearing housing, a thrust bearing anda thrust plate. The bearing housing includes a bearing cavity with alongitudinal central axis, the bearing cavity defined by an interiorhousing surface extending between an open end of the bearing housing andan interior end wall. The thrust bearing is axially disposed within thebearing cavity and includes a cup with a cup raceway, a cone with a coneraceway opposing the cup raceway, and a plurality of rollers positionedwithin the raceways. The thrust plate includes an axle engaging surfacedisposed perpendicular to the central axis and is coupled for rotationto the cone.

In yet another embodiment, a cover plate for a final drive is disclosed,the cover plate having a first end and a longitudinal central axis, thefirst end including a cover portion having a circumferential retainingflange disposed transverse to the axis. The cover plate also includes abearing housing having an axially aligned bearing cavity, the bearingcavity defined by an interior housing surface that extends between anopen end of the bearing housing and an interior end wall. A thrustbearing is disposed within the bearing housing, the thrust bearingincluding a cup with a cup raceway, a cone having a cone racewaypositioned opposing the cup raceway, and a plurality of rollerspositioned between the cup and cone raceways. A thrust plate having anaxle engaging surface disposed perpendicular to the central axis isprovided with a cylindrical extension opposite the axle engagingsurface, the cylindrical extension disposed within a bore of the conefor rotational coupling therewith.

These and other aspects and advantages of the present disclosure willbecome apparent to those skilled in the art upon reading the followingdetailed description in connection with the drawings and appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a mobile machine in accordance with oneembodiment of the present disclosure;

FIG. 2 is a perspective view of a rear drive assembly of the machine ofFIG. 1;

FIG. 3 is a side view, in cross section, of one side of the rear driveassembly of FIG. 2;

FIG. 4 is a side view, in cross section, of a cover plate and bearingassembly in accordance with one embodiment of the disclosure;

FIG. 5 is an exploded view of the cover plate and bearing assembly ofFIG. 4;

FIG. 6 is a perspective view of the interior side of a final drive coverplate in accordance with one embodiment of the disclosure;

FIG. 7A is a perspective view of a first end of a thrust plate inaccordance with one embodiment of the present disclosure;

FIG. 7B is a side view, in cross section, of the thrust plate of FIG.7A;

FIG. 7B is a perspective view of a second end of the thrust plate ofFIG. 7A.

DETAILED DESCRIPTION

An exemplary embodiment of a mobile machine 10 is shown generally inFIG. 1. The machine may be an off-highway truck, as shown, or any otheron or off-highway machine that includes a propulsion system with an axleassembly. Other exemplary machines 10 may include, for example, wheelloaders, motor graders, wheeled or tracked dozers, wheeled or trackedexcavators, water trucks, articulated trucks and similar heavy mobileequipment. Referring to FIG. 1, the exemplary off-highway truck includesa frame 12 that supports a power source (not shown) operatively coupledfor propulsion to rear wheels 14. Front wheels 16 may or may not bedriven and are operable for front-wheel steering. The frame 12 alsosupports an operator station 18 that includes the many operatorcontrols, displays and other components necessary for primary control ofthe machine during ordinary operations (not shown). For an off-highwaydump truck, the machine 10 may also include a truck body 20 for haulingmaterial, which may be tilted relative to the frame via hydraulicactuators 22 connected between the frame 12 and body 20.

The power source of the mobile machine 10 may include an engine, suchas, for example, a diesel engine, a gasoline engine, a gaseous fuelpowered engine such as a natural gas engine, or any other type of engineapparent to one skilled in the art. The power source may alternativelyinclude a non-combustion source of power such as a fuel cell, powerstorage device, electric motor, or similar mechanism. The power train ofthe machine 10 may include the power source operatively coupled through,for example, a transmission (not shown) that is mechanically connectedthrough an output shaft to a rear differential as is well known in theart. In an alternative embodiment, the machine 10 may include anelectric drive propulsion system (not shown) that includes analternator, generator, or other component configured to convertmechanical energy from the power source into electrical energy that istransferred to one or more electric drive motors for machine propulsion.Both mechanical and electrical type power trains are well known in theart.

The rear wheels 14 of machine 10 may be supported for rotation andoperatively connected to the power train through a drive assembly 30such as that shown in greater detail in FIGS. 2-3. The drive assembly 30generally includes a differential housing 32, axle shaft 34, spindle 36,final drive 38 including final drive housing 40, and wheel assembly 42.The differential housing 32 may enclose a differential (not shown)including one or more gears that transfer driving force from an inputshaft to the right and left axle shafts 34. The differential gears alsomay allow the left and right axle shafts 34 to have different rotationalvelocities for improved machine control during turning as is well knownin the art. Again, various differential configurations and componentsare well known in the art and will not be described further herein. Asshould also be apparent from FIG. 2, the rear drive assembly 30 includesopposing first and second sides 44,46, each side generally including aspindle 36, final drive 38, final drive housing 40, and wheel assembly42. Only those components for the first side shall be discussed indetail herein, the first and second sides 44,46 being substantiallyidentical. Moreover, although a differential housing 32 is shown, one ofskill in the art should readily appreciate that the differential housing32 may be replaced by a housing for one or more electric motors in thecase of an electric drive configuration (not shown). It should also beappreciated, that, for example, in an electric drive configuration, thatthe first and second sides, may be independent of one another, i.e., theopposing sides may not be connected through a common central housing.

The differential housing 32 generally includes one or more mounts 47 forconnection of the rear drive assembly 30 to the machine frame 12,typically through pivotal connections that may include one or morelinkages or suspension cylinders (not shown) that allow a degree ofmovement of rear drive assembly 30 relative to the frame 12. This mayalso allow for vertical movement of the first side 44 of the rear driveassembly 30 relative to the second side 46.

Connected to the differential housing 32 is spindle 36. The spindle 36includes a first (distal) end 48 adjacent final drive 38, and a second(proximal) end 50 that is connected to the differential housing 32. Thesecond end 50 includes an annular spindle flange 52, the flange 52having an end surface 54 for engaging mating annular surface 56 of thedifferential housing 32. Circumferentially spaced fasteners (bolts) 58connect the spindle 36 to the differential housing 32 through thespindle flange 52.

The spindle 36 provides protection and support for the axle shaft 34,FIG. 3, that is aligned within spindle axle cavity 60 along rotationalaxis 61. The axle shaft 34 is supported for rotation at a first end 62by a retainer plate 64 having an axially positioned spherical rollerthrust bearing 66, and is supported for rotation at a second end 68 by aspindle housing member 70 that has an external portion mounted to aninternal flange 72 of the spindle 36, and an axially disposed ballbearing assembly 74 that includes an axle shaft guide 76.

Disposed at the first end 62 of the axle shaft 34 is a reductive finaldrive 38 that generally includes a first reduction sun gear 78 splinedto axle shaft 34, first reduction planetary gears 80, first reductionring gear 82, first reduction planetary carrier 84, second reduction sungear 86, second reduction planetary gears 88, second reduction planetarycarrier 90, and second reduction ring gear 92. The first reduction ringgear 82 is restricted from movement and connected to the spindle 36 viareaction hub 94. First reduction sun gear 78 is rotationally coupled tothe axle shaft 34 and engages four radially disposed planetary gears 80.The planetary gears 80 include a central bore and bearing 98 forreceiving first carrier pins 96 fixedly connected to first reductioncarrier 84 for rotation of the carrier 84 about central axis 61.Extending outward from the first reduction carrier 84 is the secondreduction sun gear 86, the interior of the second reduction sun gear 86defining an axle end cavity 97. The second sun gear 86 is configured todrivingly engage second reduction planetary gears 88 that are drivinglyconnected to end wall 100 of the final drive housing 40 via secondaryplanetary pins 102, the pins 102 being supported for rotation relativeto the second reduction planetary gears 88 via pin bearings (cylindricalroller bearings) 104. Other final drive arrangements are well known inthe art.

Coaxially disposed in surrounding relationship to the spindle 36 andaxle shaft 34 is wheel assembly 42, the wheel assembly 42 primarilyserving as a connection between the final drive housing 40 and the wheelhub(s) 24, FIG. 1. More specifically, the wheel assembly 42 has firstend 106 and second end 108, the first end 106 having a circumferentialflange 110 configured for bolted engagement with final drive matingsurface 112. The bolted connection also includes a rim adapter 114having circumferential segmented components that provide the boltedattachment to an external wheel hub 24. At the second (proximal) end 108of the wheel assembly 42 is a hub flange 116 for a second (internal) huband tire (not shown). Thus, in one embodiment, each of the sides 44,46of the drive assembly 30 supports two driven tires.

The wheel assembly 42 may be supported on the spindle 36 for rotation byone or more wheel assembly bearings, such as tapered roller bearings118. In one embodiment, the drive assembly 30 may also include a brakeassembly 120 that generally includes a brake housing 122 with aplurality of brake disks 124 that may be selectively engaged by, forexample, operator controls to control braking of the machine 10 by, forexample, restricting relative movement between the spindle 36 and wheelassembly 42, as is well known in the art.

Referring again FIGS. 2-3, the final drive 38 encloses the gears,carriers, pins and other components within a final drive cavity 126defined, in part, by the first end of the wheel assembly 106, the finaldrive housing 40, the final drive end wall 100, and a cover plateassembly 127 including outer 128 and inner 130 cover plates. Generally,the cover plates 128, 130 protect the final drive components, seal thefinal drive cavity 126, and provide access to the final drive componentsand axle shaft 34 for assembly and service. In particular, the innercover plate 130 provides for access to the axle shaft 34 without havingto drain lubricant from the final drive 38. The inner cover plate 130also includes an axle end bearing assembly 132 that absorbs axial thrustand provides rotational engagement of the axle shaft 34. The outer coverplate 128, inner cover plate 130 and associated axle end bearingassembly 132 are illustrated in greater detail in FIGS. 4-6.

The inner cover plate 130 includes a first, distal end 134 that includesa retaining portion 136 that engages and provides a seal against outercover plate 128. In one embodiment, the retaining portion 136 mayinclude a circumferential retaining flange 138 that includes a pluralityof circumferentially spaced fasteners, bolts 140 with washers 142 (sixshown). However, other retaining member designs, such as a plurality ofcircumferentially spaced tabs (not shown) may be employed. An innersurface 144 of the retaining portion 136 is configured to engage amating surface 146 of the outer cover plate 128, the outer cover plate128 also having a plurality of threaded bores 148 for receivingfasteners 140. A resilient sealing member 150, such as an o-ring, may bedisposed between the inner surface 144 and mating surface 146, and may,for example, be disposed within an annular groove 151 of the innersurface 144 as shown. In the alternative, a similar groove may beprovided in connection with mating surface 146, or in both surfaces144,146.

The inner cover plate 130 also includes an axle end bearing assembly 132that generally consists of cover plate bearing housing 152, bearing 154,thrust plate 156, retainer 158 and biasing member(s) 160. The coverplate bearing housing 152 may be configured to be received within anaxial opening 162 of the larger, outer cover plate 128, the opening 162defined by a central wall portion 164 of the outer cover plate 128. Inone embodiment, the cover plate bearing housing 152 is generallycylindrical, having a first end 165, second end 167, and cylindricalouter surface 166, the cover plate bearing housing 152 being receivedwithin a corresponding circular opening 162 of the outer cover plate128. Alternative configurations for the opening and outer surface may beemployed, however, the circular configuration allows the bearing housing152 to be inserted and then rotated for aligning the threaded bores 148and fasteners 140. In this regard, threaded positioning bores 168 may beprovided, FIG. 2, for rotating and/or pulling the inner cover plate 130,or for use in supporting the weight of the cover plate 130 in connectionwith an overhead lifting device.

In yet another embodiment, the outer and inner cover plates 128, 130 maybe configured, for example, cast or welded, as a single component.However, in that case, the unitary cover plate would have to be removedin its entirety to access the bearing assembly 132, axle shaft 34 andfinal drive cavity 126, making the internal components more difficult,costly and time consuming to service.

Bearing assembly 132, including bearing 154 and thrust plate 156, isdesigned to frictionally engage and axially retain the rotating axleshaft 34, while allowing the axle shaft 34 to rotate at a significantlyhigher speed than the cover plates 128, 130 as a result of the reductivefinal drive 38. In one embodiment, the bearing 154 is a spherical rollerthrust bearing generally including a cone 170, bearing cage 172, rollers174, and bearing cup 176. “Spherical” roller bearings, as known in theart, are tapered bearings that include a longitudinal curvature to theouter surface that provides advantages over conventional taperedbearings with respect to misalignment. The cone 170 includes a first end178 having an end surface 180, and a cone bore 182 configured to receivethrust plate extension 184. In one embodiment, the cone bore 182 isdefined by a cylindrical inner surface 185. The cone 170 also includes asecond end 186 that includes the cone raceway 188, an inwardly slopedroller engaging surface relative to axis 61. The cup 176 includes acylindrical outer surface 192 and an inner sloped roller engagingsurface, cup raceway 194. The tapered rollers 174 are positioned withinannular outer cage element 190 between the cone and cup raceways, 188,194.

While other types of bearings may be employed, the spherical rollerbearing shown is configured to engage the axle shaft 34, a rotatingelement that transmits torque from the differential side gears (notshown) to the final drive sun gear 78, along with axial thrust loads asindicated at F. The spherical roller bearing has, in addition to itsaxial capacity, the ability to withstand radial loads and operate underangular misalignment of the axle shaft 34 relative to the bearing 154.One such bearing is available as part 29412E from the SKF Group ofGottenburg, Sweden.

However, those of skill in the art should appreciate that other types ofbearings, for example, roller bearings, cylindrical roller bearings andtaper bearings may be employed. Ball bearings and cylindrical rollerbearings are primarily radial bearings with limited axial forceallowances. In order to obtain the necessary axial capacity for certainapplications, these bearings may require dimensions not suitable foruse. These bearings may also be less tolerant to misalignment, resultingin undesired wear, premature failure, and increased maintenance anddowntime. Tapered bearings are also primarily a radial bearing, but havea higher allowance for axial forces. However, such bearings may notoperate in a misaligned condition, rather such bearings will prevent ortry to correct for misalignment. And, restricting the axle shaft'sdegree of freedom of movement may contribute to higher forces beingtransmitted to other components of the drive assembly.

The bearing housing 152 includes an inner surface 196 defining a bearingcavity 198 configured to slidingly receive the bearing 154 and thrustplate 156. In one embodiment, at least a first portion 200 of the innersurface 196 substantially conforms to the outer cup surface 192, theradial gap between inner surface 196 and the cup outer surface 192being, for example, 0.015 mm. The bearing housing 152 also includes aninterior end wall 202 that includes one or more cavities 204 configuredfor receiving biasing members (compression springs) 160. A plurality ofsuch cavities 204 may be disposed in spaced arrangement parallel to axis61, for example, as shown in FIG. 5, five biasing members 160 may beemployed and positioned to engage an end surface 206 of cup 176. Thesprings 160 bias the bearing 154 and associated thrust plate 156 inwardagainst the axle shaft 34 and retainer 158. Retainer 158 may, forexample, be a circlip that is disposed within a retainer groove 208 on asecond, outer portion 210 of the inner surface 196 of the bearinghousing 152.

The thrust plate 156 is depicted in greater detail in FIGS. 7A-7C. Thethrust plate 156 includes a first end 212 and second end 214, the firstend 212 configured to engage a first end 62 of axle shaft 34, while theopposing second end 214 is configured to engage bearing 154. Morespecifically, the first end 212 includes an end surface 216 thatincludes a central axle engaging surface 218 configured to frictionallyengage an end surface 230 of axle shaft 34 (FIG. 4). As shown,therefore, axle engaging surface 218 is substantially planar anddisposed perpendicular to axis 61. The axle engaging surface 218 mayhave a larger diameter than that of the axle end surface 230 to allowfor misalignment of the axle shaft 34 relative to the thrust plate 156.The thrust plate 156 may also include a circumferential retainer portion220 configured to engage retainer 158. In one embodiment, for example,the radius, R₂, of the end surface 216 may be 67 mm, where the axleshaft has a radius of approximately 48 mm. Other specific dimensionswill vary based on the application as should be appreciated by one ofskill in the art.

The first end 212 of the thrust plate 156 may include an outercylindrical surface 222 with a first inwardly tapered portion 224, thetapered portion 224 provided to enhance response to misalignment byproviding more clearance between outer cylindrical surface 222 and innersurface 196. The width W₁ of the outer cylindrical surface 222 with thetapered portion 224 may be, for example, at least 5 mm, moreparticularly 11 mm for a bronze thrust plate. As with the otherdimensions described herein, the dimension W₁ may vary depending on thespecific application, however, in this instance, the thickness should besufficient to withstand the axial forces exerted by the outward springbias against the retainer 158 without deformity and to allow a degree ofwear to the axle engagement surface 218 dependent on a number ofparameters, such as, for example, the rotational velocities, anticipatedaxial forces, material hardness, and desired component life.

The second end 214 of the thrust plate 156 is configured to engagebearing 154. First, the second end 214 may include a bearing engagingportion or surface 226 disposed perpendicular to the axis 61 of thebearing 154, opposing axle engaging surface 218. Second end 214 alsoincludes a bearing engaging extension 184 configured for positioningwithin cone bore 182, an outer surface 228 of the extension 184 being inpress fit engagement with an inner surface 232 of the cone 170 (FIG. 4).The extension may be cylindrical, with the outer surface 228 terminatingat an extension end surface 234. A second tapered portion 236 may beprovided at the edge of outer surface 228 and end surface 234 tofacilitate insertion of the extension 184 within cone bore 182. Acircumferential groove 238 may be provided at the junction betweenextension surface 228 and bearing engagement surface 226 such thatforces between the bearing 154 and thrust plate 156 are applied tosurfaces 228, 226. The radius R₁ of the extension may be, for example,about 30 mm, and the width, W₂, may be about 25 mm. In one embodiment,the dimensions of the extension are selected for a press fit associationwith the bearing cone 170. The thrust plate 156 may be constructed ofany suitable material, for example, bronze. However, in one embodiment,the thrust plate is constructed of a material having a hardness that isless than that of the axle so that wear occurs to the thrust plate 156over the axle shaft 34. For example, the thrust plate 156 may be castbronze, while the axle shaft 34 may be a steel component.

Referring again to FIGS. 4-6, to provide lubrication to the bearing 154,the bearing housing 152 may be provided with one or more lubricationchannels 242 configured to provide a flow of lubricating fluid from anexterior, for example, axle end cavity 97, to the interior bearingcavity 198 of bearing housing 152. For example, lubrication channels 242may be in spaced orientation, extending radially from axis 61 between anexterior of the housing, axle end cavity 97, and interior cavity 246 incommunication with the cup end of the bearing 154 and biasing members160.

In one embodiment, not shown, the lubrication channels 242 may leaddirectly to the interior cavity 246. However, as shown, the bearinghousing 152 may be provided with a lubrication recess 248 that isdisposed central to the interior end wall 202 along axis 61, the recess248 may include a fluid deflector 250, such as a cone-shaped deflectorthat extends outwardly along the axis 61 within the lubrication recess248. As fluid enters the outer channels 242 from the exterior cavity 97,it enters the lubrication recess 248 and is deflected inwardly towardthe bearing 154. The outer portion of the channels 242 adjacent theouter surface of the housing may include a funnel-shaped opening 252 tofacilitate capture and entry of lubricating fluid.

The interior of the outer cover plate 128 includes an annular ring 254that protrudes from an inwardly protruding cone section 256. The ring254 forms a seal against an end surface 266 of second sun gear 86,thereby enclosing axle end cavity 97 (FIG. 3). To allow lubricatingfluid to enter the axle end cavity 97, a series of circumferentiallyspaced, radially oriented recesses 258 are provided in the ring 254.Thus, lubricating fluid can pass from final drive cavity 126 through therecesses 258 of the outer cover plate 128 churned by the rotatingplanetary gears 80, 86 to the axle end cavity 97 as the outer coverplate 128 rotates. The lubricating channels 242 may be positioned inplanar relationship to the recesses 258 of the outer cover plate 128 tofacilitate capture of lubricant entering the axle end cavity 97.

The spherical thrust bearing 154 acts as a pump for lubricating fluidentering inner cavity 246. As the bearing rotates, the tapered rollerscreate a flow of fluid from the cup end of the bearing 154 through thecage 172 and between the cup and cone raceways 188,194 into outer cavity244. Fluid flows from the outer cavity 244 through evacuation channels240 that are provided between the outer cavity 244 and the axle endcavity 97. A number of evacuation channels 240 may be provided in spacedrelationship about the circumference of the bearing housing 152, and maybe aligned with the lubrication channels 242. The evacuation channels240 provide a primary fluid path, alleviating pressure build up thatcould occur in the absence of such channels 240.

One of the many benefits of the disclosed designs is to provide abearing assembly that is conveniently assembled and maintained.Referring again to FIG. 5, once the internal components of the finaldrive 38, including, among others, the planetary gears 80, 88, carriers84,90, pins 96,102 and bearings 98,104 are assembled, outer cover plate128 may be fastened to the end wall 100 of the final drive housing 40via circumferentially positioned fasteners, bolts 140. Inner cover plate130 may be assembled by positioning biasing members 160 within cavities204 of interior end wall 202, and then sliding the pre-assembled bearing154 and thrust plate 156 into position against the biasing members 160,the thrust plate extension 184 being press-fit within the bore 182 ofthe cone 170. Thrust plate 156/bearing 154 may then be forced inwardagainst the bias of springs 160 and retainer 158 positioned withinretainer groove 208, the springs 160 maintaining a pre-load on thebearing 154 and forcing the retainer portion 220 of the thrust plate 156against portions of retainer 158 extending beyond groove 208. Sealingmember 150 may then be inserted within groove 151 to complete assemblyof the inner cover plate 130 Inner cover plate 130 may then bepositioned within axial opening 162 and rotated into position employingthreaded members (not shown) inserted within positioning bores 168.Fasteners 140 may then be employed to secure the inner cover plate 130against inner surface 144 of the outer cover plate 128. The end surface230 of axle shaft 34 may be pressed against thrust plate axle engagingsurface 218, forcing the thrust plate 156 and bearing 154 inward againstbiasing members 160, displacing the thrust plate 156 off the retainer158.

During operation, axle shaft 34, operatively connected to the powersource and through the differential (not shown), may be driven at afirst rate of rotation, for example, up to 1500 rpm. Rotation istransferred through the final drive reduction such that the end wall 100of final drive housing 40, wheel assembly 42, and connected outer 128and inner cover plates 130 are driven at a second rotational velocity,for example, at about 92 rpm at a potential maximum velocity. The ratioof rotational velocity of the axle shaft 34 to the wheel assembly 42 maybe, for example, about 17 to 1. The thrust plate 156 is frictionallyengaged with, and rotates together with the end surface of axle shaft230, together with the attached bearing cone 170, while the bearing cup176 is rotationally engaged with the biasing members 160 and rotatingcover plates 128, 130. Thus, the axle end bearing assembly 132 providesfor axial retention of the axle shaft 34, while allowing relativerotation of the axle shaft 34 and inner cover plate 130, reducingcomponent wear.

In an alternative design, the axle shaft 34 could be fixedly connectedto a bearing component and cover plate assembly 127. However, onebeneficial aspect of the present detached design is that it allows forgreater manufacturing tolerances and misalignment with respect to theaxle shaft 34 and the axle end bearing assembly 132 that may occur whenyou have numerous components to be assembled.

During operation, wear may occur to the thrust plate 156, particularlyto axle engaging surface 218, and the thrust plate 156 and bearing 154may require periodic replacement. The disclosed design provides aconvenient means for replacement without having to drain lubricatingfluid from the final drive cavity 126 when machine 10 is positioned on alevel surface. Drain port 264 may be rotated to a lower position todrain lubricating fluid to a sufficient level for removal of the innercover plate 130 in some applications, either due to overall design or anuneven surface. The inner cover plate 130 may then be removed viafasteners 140 and disassembled. In another embodiment, provided is arebuild kit that may include a replacement thrust plate 156, bearing154, retainer 158 and sealing member 150. Such a kit could also includethe biasing members 160.

INDUSTRIAL APPLICABILITY

The present disclosure provides a cover plate and bearing assembly foruse in connection with mobile machinery, particularly those that includea power train including a final drive disposed between an axle shaft andthe driven traction devices of the machine. More particularly, thedisclosed design provides a cover plate assembly 127 having an outercover plate 128 and an inner cover plate 130 mounted to the exterior ofa final drive housing 40 (FIG. 2). The inner cover plate 130 includes abearing 154 and thrust plate 156 positioned within a bearing housing152, the thrust plate 156 and bearing 154 axially aligned to engage anend surface 230 of a rotating axle shaft 34 to axially retain the shaftand allow rotation of the axle shaft 34 relative to the cover plate 130(FIG. 4-5). This results in less stresses placed upon the axle shaft 34and less wear to internal components caused by engagement of the axleshaft 34 and cover plate 130 in conventional designs. In addition, theinner cover plate 128 may be removed for maintenance or replacement ofthe bearing assembly 132 and axle shaft 34, without having to remove theouter cover plate 128 and draining all of the lubricating fluid from thefinal drive housing 40. The overall result is decreased machinemaintenance costs, increased productivity, and improved system andenvironmental cleanliness.

The disclosed design also provides a system for lubricating the bearing154 and associated components. The bearing housing 152 includes one ormore lubrication channels 242 that are in fluid communication with alubrication recess 248 having a fluid deflector 250 to deliverlubricating fluid to the cup 176 end of the bearing during rotation ofthe inner cover plate 130, fluid moved via pumping action of the bearing154 to an outer cavity 244 which may be provided with one or moreevacuation channels 240. This provides improved lubrication for the axleend bearing assembly and axle shaft 34, increasing component life.

It should be understood that the above description is intended forillustrative purposes only. While aspects of the present disclosure havebeen particularly shown and described with reference to the embodimentsabove, it will be understood by those skilled in the art that variousadditional embodiments may be contemplated by modification of thedisclosed components and methods without departing from the spirit andscope of what is disclosed. Such embodiments should be understood tofall within the scope of the present invention as determined based uponthe claims below and any equivalents thereof.

1. A drive assembly for a mobile machine, comprising: an axle shafthaving an outer end and a central axis; a final drive having a pluralityof gears operatively connected to the axle shaft and contained within afinal drive housing, a cover plate assembly connected to the final drivehousing, the cover plate assembly including: a bearing housing having afirst end, a second end, and an axially aligned bearing cavity, thebearing cavity defined by an interior housing surface extending betweenan opening at the second end of the bearing housing and an interior endwall; a thrust bearing axially disposed within the bearing cavity, thethrust bearing including a cup with a cup raceway, a cone having a coneraceway positioned opposing the cup raceway, and a plurality of rollerspositioned between the cup and cone raceways; a thrust plate having anaxle engaging surface disposed perpendicular to the central axis, thethrust plate being coupled for rotation to the cone, wherein the outerend of the axle shaft rotationally engages the axle engaging surface. 2.The drive assembly of claim 1, wherein the cover plate assembly includesan outer cover plate and an inner cover plate fastened to the outercover plate, the outer cover plate including an axial opening, thebearing housing extending from a first end of the inner cover plate anddisposed within the axial opening.
 3. The drive assembly of claim 2,wherein the first end of the inner cover plate includes a radiallyextending retaining portion, the inner cover plate being fastened to theouter cover plate at the retaining portion.
 4. The drive assembly ofclaim 3, wherein the retaining portion is a radially extendingcircumferential flange.
 5. The drive assembly of claim 1, wherein thethrust plate includes an axially aligned extension disposed opposite theaxle engaging surface, the cone including an axial bore that receivesand frictionally engages the thrust plate extension.
 6. The driveassembly of claim 1, wherein the interior housing surface includes anannular retaining groove disposed proximal the opening, a retainerdisposed within the retaining groove and configured to retain the thrustplate and associated bearing within the bearing cavity.
 7. The driveassembly of claim 6, wherein the bearing housing includes a biasingmember positioned between the interior end wall and the cup, the biasingmember biasing the thrust plate toward the retainer.
 8. The driveassembly of claim 1, wherein the cover plate housing includes aplurality of lubrication channels extending from an outer surface of thebearing housing to the bearing cavity.
 9. The drive assembly of claim 8,the interior end wall of the bearing cavity including an annularlubrication recess with an axially aligned deflector, the lubricationchannels extending to the lubrication recess.
 10. A cover plate for adrive assembly, comprising: a bearing housing having a bearing cavitywith a longitudinal central axis, the bearing cavity defined by aninterior housing surface extending between an open end of the bearinghousing and an interior end wall; a thrust bearing axially disposedwithin the bearing cavity, the thrust bearing including a cup with a cupraceway, a cone having a cone raceway positioned opposing the cupraceway, and a plurality of rollers positioned between the cup and coneraceways; a thrust plate having an axle engaging surface disposedperpendicular to the central axis, the thrust plate being coupled forrotation to the cone.
 11. The cover plate of claim 10, furthercomprising a retaining portion extending radially from a first end ofthe cover plate, the bearing housing extending axially from the firstend of the cover plate.
 12. The cover plate of claim 11, wherein theretaining portion is a circumferential flange.
 13. The cover plate ofclaim 10, wherein the thrust plate includes an axially alignedextension, the cone including an axial bore defined by a bore innersurface that receives and frictionally engages the thrust plateextension.
 14. The cover plate of claim 10, wherein the interior housingsurface includes an annular retaining groove disposed proximal the openend, a retainer disposed within the retaining groove and configured toretain the thrust plate and associated bearing within the bearingcavity, a biasing member positioned between the interior end wall andthe cup, the biasing member biasing the thrust plate towards theretainer.
 15. The drive assembly of claim 10, wherein the cover platehousing includes a plurality of lubrication channels extending from anouter surface of the bearing housing to the bearing cavity.
 16. Thedrive assembly of claim 15, the interior end wall of the bearing cavityincluding a lubrication recess with an axially aligned deflector, thelubrication channels extending to the lubrication recess.
 17. A coverplate for a final drive, comprising: a first end and a longitudinalcentral axis, the first end including a cover portion having acircumferential retaining flange disposed transverse to the axis; abearing housing having an axially aligned bearing cavity, the bearingcavity defined by an interior housing surface extending between an openend of the bearing housing and an interior end wall; a thrust bearingaxially disposed within the bearing cavity, the thrust bearing includinga cup with an inwardly facing cup raceway, a cone having an outwardlyfacing cone raceway positioned opposing the cup raceway, and a pluralityof rollers positioned between the cup and cone raceways; a thrust platehaving an axle engaging surface disposed perpendicular to the centralaxis, the thrust plate having a cylindrical extension opposite the axleengaging surface, the cylindrical extension disposed within a bore ofthe cone for rotational coupling therewith.
 18. The cover plate of claim17, further comprising a plurality of lubrication channels radiallyextending between an outer surface of the bearing housing and thebearing cavity.
 19. The cover plate of claim 18, wherein the lubricationchannels extend to a first portion of the bearing cavity adjacent thecup, the bearing housing further including a plurality of evacuationchannels extending between the outer surface of the bearing housing anda second portion of the bearing cavity between the opening and the cone.20. The cover plate of claim 18, wherein the interior end wall of thebearing cavity includes a lubrication recess with an axially aligneddeflector, the lubrication channels extending to the lubrication recess.